Emergency brake control system

ABSTRACT

A fluid pressure emergency brake control system has a novel valving arrangement which permits the operator of a vehicle to apply and release the brakes so long as the fluid pressure in the system is above a predetermined level and after the fluid pressure drops below the predetermined level only allows the operator to apply the brakes.

llnite States Patent 1 1 worm Inventors Curtis F. Cummins Decatur;

Kenneth W. Kelly, Latham; Larry G. Warren, Peoria, all of, 111. Appl.No. 824,937 Filed May 15, 1969 Patented Aug. 24, 1971 AssigneeCaterpillar Tractor Co. Peoria, H1.

EMERGENCY BRAKE CONTROL SYSTEM 6 Claims, 2 Drawing Figs.

11.8. C1 303/13, 303/2, 303/9 1m. CI B60t 13/28 Field 01' Search 303/13,2, 9.7

[56] References Cited 1 UNITED STATES PATENTS 3,228,729 1/1966 Schubert303/9 3,237,995 3/1966 Dobrikin 303/13 X 3,273,950 9/1966 Vielmo 303/93,294,455 12/1966 Valentine 303/9 3,443,839 5/1969 Hinrichs et al 303/13X Primary Examiner-Milton Buchler Assistant Examiner-John J. McLaughlinArlorneys' Fryer, Tjensvold, Feix, Phillips & Lempio ABSTRACT: A fluidpressure emergency brake control system has a novel valving arrangementwhich permits the operator of a vehicle to apply and release the brakesso long as the fluid pressure in the system is above a predeterminedlevel and after the fluid pressure drops below the predetermined levelonly allows the operator to apply the brakes.

FRONT BRAKE MASTER l CYLINDER 44 F RONT *i BRAKE MASTER REAR CYLINDERBRAKE EMERGENCY BRAKE CONTROL SYSTEM BACKGROUND OF THE INVENTION Thisinvention relates to an emergency brake control system for highwayvehicles such as large trucks and the like. More particularly theinvention is directed to an emergency brake control system which willallow the operator of the vehicle a greater degree of control over brakeapplication and release during an emergency situation than hasheretofore been possible with conventional emergency brake systems.

One of the primary drawbacks of present day emergency brake systems isthe lack of operator control over brake application in an emergencysituation. In many emergency brake systems the operator is suddenlywarned that a failure has occurred in the main brake system and that thevehicle can only be stopped by operating the emergency brakes. In theseprior art systems the operator has little control over the applicationof the brakes during an emergency. That is, the operator can only decidewhen" to apply the emergency brakes. One the brakes are applied throughthe emergency system the operator cannot release the brakes. This canlead to serious con sequences due to skidding and loss of control of thevehicle. Such a single application emergency brake system can beespecially dangerous on wet or icy pavement where a sudden locking ofthe brakes can easily cause the operator to lose control of the vehicle.

The principal object of the present invention is the provision of anemergency brake control system which will allow the operator toselectively apply and release the brakes a plurality of times in orderto safely bring the vehicle to a controlled stop.

A further object of the invention is the provision of an adequatewarning system which will firstly alert the operator of a failure in themain brake system and secondly alert the v operator after several brakeapplications through the emergency system that it will not be possibleto release the brakes after the next application thereof.

Other and further objects and advantages of the present invention willbe apparent from the following description and claims and areillustrated in the accompanying drawings which, by way of illustration,show preferred embodiments of the present invention and the principlesthereof and what are now considered to be the best modes contemplatedfor applying these principles. Other embodiments of the inventionembodying the same or equivalent principles may be used and structuralchanges may be made as desired by those skilled in the art withoutdeparting from the present invention and the purview ofthe appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an overall schematic viewillustrating the major components of both the standard brake system andan emergency brake control system for a vehicle; and,

FIG. 2 is a cross-sectional view illustrating the structural details ofa preferred form of inversion valve which may be used in the emergencybrake control system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, aconventional air compressor supplies air under pressure to a main airpressure reservoir 22. The main air pressure reservoir 22 is providedwith a safety valve 24 which prohibits a buildup of air pressure in themain reservoir in excess of 150 p.s.i.

A conduit 26 leads from the main reservoir 22 to a junction connection28. During normal operation air under pressure is supplied from thereservoir 22 through the foot-operated 26 and junction 28 to a conduit30 and a conduit 32.

A pressure protection valve 34 is located in the conduit 30. Thepressure protection valve 34 is normally open to supply air pressure toa conduit 36 which leads to an emergency brake control system which willbe described in greater detail at a later point in the description.However, at this point it should be noted that the pressure protectionvalve 34 closes off supply of air pressure to the conduit 36 wheneverthe delivery pressure in conduit 26 falls below a predetermined value,for example, 60 p.s.i.

Under normal operating conditions air pressure will be supplied to themain brake system of the vehicle by way of the conduit 32. Conduit 32leads to a foot-operated brake valve 40. The foot-operated brake valve40 is operable to deliver air pressure to a conduit 42 and a conduit 44.

The conduit 42 communicates with branch conduits 46 and 48 which in turncommunicate with the rear brake master cylinders via double-check valvesshown at 50. The double check valves 50 are conventional shuttle-typevalves which allow two separate supply sources to be combined to onedelivery port. The double-check valves also block open or unusedconduits.

The conduit 44 communicates air pressure from the foot operated brakevalve 40 to a normally open hand-operated front wheel brake cutout valve56 and then to a double-check valve 58 which in turn communicates withthe master cylinder for the front brakes of the vehicle.

During normal operation of the main brake system depression of thefoot-operated brake 40 warning both the rear and front brakes to adegree proportional to the amount of depression of the brake valve 40.During certain operations of the vehicle it may be desirable to applyonly the rear brakes and during these instances the hand-operated frontwheel brake cutout valve 56 is moved to a closed position therebypreventing air pressure from passing through the downstream side of theconduit 44 to the master cylinder for the front brakes. It should alsobe noted that the supply port of the brake valve 40 communicates with apressure switch 47 which actuates a warning light and buzzer assembly(not shown) in the vehicle cab when the air pressure in conduit 32 dropsbelow a predetermined value, for example 60 p.s.i.

Returning now to the emergency brake control system it will be recalledthat air pressure from the reservoir 22 communicates through the conduit26 to the conduit 30 through the normally open pressure protection valve34 which delivers air pressure to a conduit 36. The conduit 36 branchesinto conduits 62 and 64.

The conduit 62 communicates air pressure through a check valve 66 to arear brake emergency reservoir 68. The purpose of the check valve 66 isto maintain a certain predetermined pressure in the emergency reservoir68. For example, the check valve 66 could be set to close at any timethe pressure in the conduit 36 drops below a given value which might be120 p.s.i.

The conduit 62 leads from the emergency reservoir 68 to a supply port 69of an inversion valve 70. A branch conduit 72 communicates the conduit62 with a safety relief valve 74 which exhausts air pressure from thereservoir 68 when the pressure in the reservoir exceeds a predeterminedvalue, for example 150 p.s.i. Another branch conduit 76 communicates theconduit 62 with a pressure switch 78. The pressure switch 78 is set toactuate a horn 80 when the pressure in the emergency system descendsbelow a predetermined value.

The branch conduit 64 also leads through a check valve 66 andcommunicates with a supply port 83 of an inversion valve 84. A branchconduit 86 leads from conduit 64 and communicates a front brakeemergency reservoir with a normally open pressure protection valve 90which may be set to close when the pressure in conduit 86 drops below apredetermined value, for example 60 p.s.i.

A branch conduit 92 communicates the conduit 86 with a safety reliefvalve 94 which functions like the valve 74 to exhaust air pressure fromthe reservoir 88 when the pressure in the reservoir 88 exceeds apredetermined value, for example p.s.i. Another branch conduit 96communicates the conduit 86 with a pressure switch 98. The pressureswitch 98 is similar to the pressure switch 78 and is set to actuate awarn ing light 100 when the pressure in the emergency system descendsbelow a predetermined value.

The conduit 86 leads from the normally open pressure protection valve 90to a supply port of normally open handoperated emergency control valve104. The normally open emergency control valve 104 delivers air pressureto a conduit 106. The conduit 106 communicates with a conduit 108 whichdelivers air pressure to a control port 107 of the inversion valve 70Conduit 106 also communicates with a conduit 110 which delivers airpressure to a control port 109 of the inversion valve 84.

The inversion valve 70 is provided with a delivery port 111 which cansupply air pressure to a conduit 112 during an emergency situation. Theconduit 112 communicates with a branch conduit 114 which communicatesair pressure to the rear brakes via double-check valves 50 during anemergency situation.

Similarly, the inversion valve 84 is provided with a delivery port 115which supplies air pressure to a conduit 118 during an emergencysituation. The conduit 118 communicates air pressure to the front brakesvia double check valve 58 during an emergency.

Referring now to FIG. 2 the details of the construction of the inversionvalves 70 and 84 will be explained. The descrip tion will be directed toinversion valve 84, it being understood that the valve 70 has identicalcomponents.

The inversion valve 84 comprises a main housing 126 which is providedwith a central bore 128. The bore 128 has an enlarged diameter portion130 which receives the enlarged end 132 ofa movable valve spool 134. Acoil spring 136 is retained in the lower end of the enlarged bore 130 bymeans ofa conventional spring retainer assembly 138.

The spring retainer 138 has holes or slots formed in its lower end. Ifsufficient air pressure builds up in the enlarged bore 130 a flexiblerubber diaphragm member 142 will allow air to be exhausted from theenlarged bore, The upper end of the coil spring 136 is received in arecessed portion 144 of the valve spool 134.

It should be noted that the rod portion of the spool 134 is providedwith a hollow bore 146. At the upper end 148 of the housing bore 128 aspring retainer 150 having a central orifice 152 retains a small coilspring 154. The lower end of the coil spring 154 is provided with awasher seal 156 which is normally biased downwardly.

Under normal circumstances (that is, in a nonemergency situation) airpressure at approximately 120 p.s.i. will be communicated through theconduit 64 to the supply port 83 of the inversion valve 84. This airpressure in conduit 64 will either be transmitted from the emergencyreservoir 88 via the conduit 86 or ifthe check valve 66 is open then theair pressure in the conduit 64 will be transmitted from the main brakecircuit via the conduit 26 which is in communication with the mainreservoir 22.

In addition, air pressure at 120 p.s.i. will be transmitted from theemergency reservoir 88 to the conduit 86 through the normally openpressure protection valve 90 and on to the supply and delivery ports ofthe normally open emergency control valve 104. Emergency control valve104 transmits this air pressure to conduit 106 and finally to theconduit 110 which is in communication with the control port 109 of theinversion valve 84.

The control port 109 communicates air pressure from the conduit 110 tothe upper surface of the enlarged end 132 of the valve spool 134. At anytime when the air pressure in the control port 109 descends toapproximately 45 p.s.i. the coil spring 136 will actuate the spool 134upwardly to the position shown in FIG. 2. That is, the spool will moveupwardly so that the upper end of the spool 134 engages the washer seal156 thereby closing off the internal bore 146 of the spool andsimultaneously moving the washer seal upwardly to permit air pressure tobe transmitted from the supply port 83 to the delivery port 115. Duringthis condition of the inversion valve 84, air pressure from theemergency reservoir 88 is transmitted to the conduit 64, supply port 83,delivery port 115 and conduit 1 18 to apply the front brakes as shown inFIG. 1.

If the pressure at the control port 109 ascends to approximately 65p.s.i. the air pressure on the enlarged end 132 of the spool 134overcomes the bias of coil spring 136 and the spool is moved downwardlyin the enlarged bore 130. At this time the washer seal 156 is biased bythe spring 154 to close off the supply port 83 from the delivery port115. When the spool 134 is moved to this lower position under theinfluence of the pressure at the control port 109, the supply port 115exhausts air pressure from the brake delivery conduit 118 via theinternal bore 146 of the spool and the flexible diaphragm 142.

The overall operation of the emergency brake control system is asfollows. At any time the pressure in the main brake system drops belowapproximately 60 p.s.i. the pressure protection valve 34 will close andthe pressure switch 47 will actuate a warning light and buzzer assemblyin the cab of the vehicle thereby warning the operator that only 60p.s.i. are available in the main brake system. Prior to this time thecheck valves 66 move to a closed position to insure that at least 120p.s.i. are maintained in the emergency reservoirs 68 and 88 of theemergency brake control system.

The operator of the vehicle may now move a lever 105 on the normallyopen emergency control valve 104 to close the valve which blocks off theconduit 86 and opens the conduit 106 to the exhaust port of the valve104. Exhausting air from the conduit 106 results in an immediate drop inthe air pressure at the control ports 107 and 109 of the inversionvalves 69 and 84. Once the pressure at the control ports 107 and 109drops below 45 p.s.i., 120 p.s.i. is communicated from the emergencyreservoir through the conduits 62 and 64 to the supply ports 69 and 83then to the delivery ports 111 and 115, and finally to the front andrear brakes via the conduits 118 and 112.

The operator may disengage the brakes by releasing the spring biasedlever 105 of the emergency control valve 104 which automatically opensthe supply port of the emergency control valve to the pressure inconduit 86 which pressure is transmitted trough the conduit 106 to thecontrol ports 107 and 109 of the inversion valves 70 and 84. So long asthe pressure at the control ports 107 and 109 exceeds 65 p.s.i. theinversion valves will function to block delivery from the supply ports69 and 83 to the brake delivery ports 111 and 115.

Thus, the operator ofthe vehicle will have an opportunity to apply andrelease the front and rear brakes via the emergency control systemseveral times depending upon the capacity of the emergency reservoirs 68and 88. However, once the pressure in the emergency reservoirs dropsbelow 60 p.s.i. the pressure switches 78 and 98 will actuate the hornand warning light 100 indicating to the operator that he will not beable to release the brakes if they are applied again. At this time thenormally open pressure protection valve will also move to a closedposition since the pressure in the conduit 86 has dropped below 60p.s.i. Stated otherwise, after several applications of the emergencybrakes via the emergency control system the pressure in the emergencycontrol system will drop to a danger point whereby the operator will nolonger be able to release the brakes if he applies them.

While we have illustrated and described preferred embodiments of ourinvention, it is to be understood that these are capable of variationand modification, and we therefore do not wish to be limited to theprecise details set forth, but desire to avail ourselves of such changesand alterations as fall within the purview of the following claims.

1. An emergency brake control system for selectively applying andreleasing the pressure actuated brakes of a vehicle when failure occursin a primary brake control system com prising;

emergency reservoir means having pressure fluid normally maintained at afirst predetermined pressure independent of the pressure level of theprimary brake control system;

conduit means for selectively communicating pressure fluid from theemergency reservoir means to the pressure-actuated brakes to apply saidbrakes; and

emergency control means in fluid communication with the conduit meansand including a manually operable emergency control valve which permitsan operator of the vehicle to selectively apply and release the brakeswhen the emergency reservoir pressure is above a second 5 predeterminedpressure which is lower than the first predeterminedpressure, and afterthe emergency reservoir pressure drops below the second predeterminedpressure only permitting the operator to apply the brakes.

2. A fluid-actuated emergency brake control system for selectivelyapplying and releasing the pressure actuated brakes of a vehicle whenfluid pressure in a primary brake control system drops below apredetermined level comprising:

emergency reservoir means;

first conduit means for normally communicating pressure fluid to theemergency reservoir means from a fluid pressure source which source alsosupplies pressure fluid to the primary brake control system;

First valve means for maintaining a first predetermined pressure in theemergency reservoir means independent of the pressure in the primarybrake control system;

second conduit means for selectively communicating pressure fluid fromthe emergency reservoir means to said pressure-actuated brakes to applysaid brakes; and,

emergency control means in fluid communication with the second conduitmeans and including a manually operable emergency control valve whichpermits an operator of the vehicle to selectively apply and release thebrakes when the emergency reservoir pressure is above a secondpredetermined pressure which is lower than the first predeterminedpressure, and after the emergency reservoir pressure drops below thesecond predetermined pressure only permitting the operator to apply thebrakes. 3. A fluid-actuated emergency brake control system forselectively applying the pressure actuated brakes of a vehicle whenfluid pressure in a primary brake control system drops below apredetermined level comprising:

and a delivery port;

second conduit'means communicating fluid pressure from the emergencyreservoir to the supply port of the inversion valve;

a manually operable emergency control valve having a supply port,delivery port, and exhaust port;

third conduit means communicating the emergency reservoir with thesupply port of the emergency control valve;

fourth conduit means communicating the delivery port of the emergencycontrol valve with the control port of the inversion valve;

fifth conduit means communicating the delivery port of the inversionvalve with the pressure-actuated brakes of the vehicle;

said emergency control valve operable to permit an operator of thevehicle to selectively exhaust pressure fluid from the fourth conduitmeans;

said emergency control valve having a normally open condition totransmit emergency reservoir pressure through the fourth conduit to thecontrol port of the inversion valve;

the inversion valve having a normal operating condition wherein so longas the pressure in the fourth conduit is above a second predeterminedpressure, the delivery port of the inversion valve will not communicatepressure fluid from the emergency reservoir to the brakes;

said inversion valve having a second operating condition such that ifthe pressure in the fourth conduit drops below the second predeterminedpressure the delivery port of the inversion valve Wlll supply emergencyreservoir pressure to the brakes through the fifth conduit to apply saidbrakes.

4. An emergency brake control system as set forth in claim 3 whereinindicator means are provided in the cab of the vehicle to alert theoperator of the vehicle when the pressure in the primary brake controlsystem has dropped below a predetermined level.

5. An emergency brake control system as set forth in claim 4 whereinsecond indicator means are located in the cab of the vehicle to alertthe operator when the pressure in the emergency reservoir has droppedbelow the second predetermined pressure.

6. An emergency brake control system as et forth in claim 3 whereinindicator means are located in the cab of the vehicle to alert theoperator when the pressure in the emergency reservoir has dropped belowthe second predetermined pressure.

1. An emergency brake control system for selectively applying andreleasing the pressure actuated brakes of a vehicle when failure occursin a primary brake control system comprising; emergency reservoir meanshaving pressure fluid normally maintained at a first predeterminedpressure independent of the pressure level of the primary brake controlsystem; conduit means for selectively communicating pressure fluid fromthe emergency reservoir means to the pressure-actuated brakes to applysaid brakes; and emergency control means in fluid communication with theconduit means and including a manually operable emergency control valvewhich permits an operator of the vehicle to selectively apply andrelease the brakes when the emergency reservoir pressure is above asecond predetermined pressure which is lower than the firstpredetermined pressure, and after the emergency reservoir pressure dropsbelow the second predetermined pressure only permitting the operator toapply the brakes.
 2. A fluid-actuated emergency brake control system forselectively applying and releasing the pressure actuated brakes of avehicle when fluid pressure in a primary brake control system dropsbelow a predetermined level comprising: emergency reservoir means; firstconduit means for normally communicating pressure fluid to the emergencyreservoir means from a fluid pressure source which source also suppliespressure fluid to the primary brake control system; First valve meansfor maintaining a first predetermined pressure in the emergencyreservoir means independent of the pressure in the primary brake controlsystem; second conduit means for selectively communicating pressurefluid from the emergency reservoir means to said pressure-actuatedbrakes to apply said brakes; and, emergency control means in fluidcommunication with the second conduit means and including a manuallyoperable emergency control valve which permits an operator of thevehicle to selectively apply and release the brakes when the emergencyreservoir pressure is above a second predetermined pressure which islower than the first predetermined pressure, and after the emergencyreservoir pressure drops below the second predetermined pressure onlypermitting the operator to apply the brakes.
 3. A fluid-actuatedemergency brake control system for selectively applying the pressureactuated brakes of a vehicle when fluid pressure in a primary brakecontrol system drops below a predetermined level comprising: a source ofpressure fluid; emergency reservoir means; first conduit means fornormally communicating pressure fluid to the emergency reservoir meansfrom the fluid pressure source; first valve means for maintaining afirst predetermined pressure in the emergency reservoir meansindependent of the pressure at the fluid pressure source; inversionvalve means having a supply port, a control port, and a delivery port;second conduit means communicating fluid pressure from the emergencyreservoir to the supply port of the inversion valve; a manually operableemergency control valve having a supply port, delIvery port, and exhaustport; third conduit means communicating the emergency reservoir with thesupply port of the emergency control valve; fourth conduit meanscommunicating the delivery port of the emergency control valve with thecontrol port of the inversion valve; fifth conduit means communicatingthe delivery port of the inversion valve with the pressure-actuatedbrakes of the vehicle; said emergency control valve operable to permitan operator of the vehicle to selectively exhaust pressure fluid fromthe fourth conduit means; said emergency control valve having a normallyopen condition to transmit emergency reservoir pressure through thefourth conduit to the control port of the inversion valve; the inversionvalve having a normal operating condition wherein so long as thepressure in the fourth conduit is above a second predetermined pressure,the delivery port of the inversion valve will not communicate pressurefluid from the emergency reservoir to the brakes; said inversion valvehaving a second operating condition such that if the pressure in thefourth conduit drops below the second predetermined pressure thedelivery port of the inversion valve will supply emergency reservoirpressure to the brakes through the fifth conduit to apply said brakes.4. An emergency brake control system as set forth in claim 3 whereinindicator means are provided in the cab of the vehicle to alert theoperator of the vehicle when the pressure in the primary brake controlsystem has dropped below a predetermined level.
 5. An emergency brakecontrol system as set forth in claim 4 wherein second indicator meansare located in the cab of the vehicle to alert the operator when thepressure in the emergency reservoir has dropped below the secondpredetermined pressure.
 6. An emergency brake control system as et forthin claim 3 wherein indicator means are located in the cab of the vehicleto alert the operator when the pressure in the emergency reservoir hasdropped below the second predetermined pressure.